The stakes are enormous. In small-scale, tropical, and data-poor fisheries, roughly one-quarter to one-third of freshwater fish species are threatened with extinction once so-called Data Deficient species are properly accounted for, and 37.5 percent of sharks and rays face a similar fate. These are precisely the systems where conventional monitoring and stock-assessment tools, which demand years of standardized catch data, expensive survey vessels, and teams of trained technicians, are financially and technically out of reach. Managers are left without the evidence they need to prioritize conservation action or to implement even basic precautionary governance. The result is a paradox that has haunted tropical conservation for decades: the places with the richest biodiversity are often the places with the thinnest scientific records.

Local Ecological Knowledge, or LEK, offers a way out of that paradox. The term refers to the cumulative understanding that resource users develop through direct, repeated observation of their environment, often across generations. Fishers know where giant guitarfish once gathered, when sawfish stopped appearing in their nets, and how the largest catfish of the Mekong have thinned year after year. Unlike a scientific survey that captures a single snapshot in time, LEK carries temporal depth, spatial resolution, and species-specific detail that no research program could afford to collect on its own. The new review demonstrates that this knowledge is not anecdote but data, provided it is collected and analyzed with the same rigor that ecologists apply to any other measurement.

The authors screened and synthesized sixty studies published between 1997 and 2025, all of which applied LEK to assess the conservation status of fish. Using systematic review methods aligned with established reporting guidelines, combined with a bibliometric analysis of how the field has grown and clustered, the team identified four complementary pathways through which fishers’ knowledge informs conservation management. The first is reconstructing multi-decadal population changes: fishers can describe how catches of a given species have shifted across their working lives, effectively extending monitoring back to a period before any scientist was watching. Studies from the Mediterranean, southeastern Brazil, and the Gulf of California have used this approach to quantify declines of long-lived species over timescales that would otherwise be invisible.

The second pathway is documenting spatial contraction and habitat loss. Fishers’ accounts can reveal where species once occurred and where they have disappeared, generating maps of range collapse that are essential for prioritizing protected areas. Research in the Andaman Islands used local knowledge to chart the distribution of the critically endangered giant guitarfish, while studies in Fiji identified shark river habitats that formal surveys had missed entirely. The third pathway is detecting extreme rarity and local extirpation. Because fishers sample the water continuously and at low cost, they are often the first to notice that a species has gone from uncommon to absent. The regional disappearance of the largetooth sawfish from the central coast of Brazil, and the vanishing of sawfishes from Sri Lanka and Liberia, were documented primarily through fishers’ testimony.

The fourth pathway is perhaps the most technically sophisticated: characterizing a species’ intrinsic sensitivity to exploitation based on life-history traits. Fishers who have handled a species for decades know how often it reproduces, how large it grows, and how vulnerable it is to capture, information that feeds directly into frameworks for estimating extinction risk. When combined with formal risk-assessment methods, this knowledge allows researchers to evaluate species that have never been formally assessed. The review notes that this approach has proven especially valuable for elasmobranchs, the sharks and rays, whose slow growth and low reproductive rates make them acutely sensitive to overfishing and whose cryptic habits make them difficult to study by conventional means.

Methodological rigor in the field has grown markedly over the review period. Early studies relied heavily on informal interviews and anecdotal recollection, which critics warned were vulnerable to shifting baseline syndrome, the gradual recalibration of what fishers consider a normal abundance as each generation inherits a degraded environment. Later work has responded with structured and semi-structured questionnaires, participatory mapping, calibration against independent scientific surveys, and integration into formal modeling frameworks such as management strategy evaluation. Studies that compared fishers’ knowledge directly with fish sampling results found substantial agreement, lending quantitative weight to what practitioners had long suspected: experienced resource users are, in effect, highly skilled biological observers.

Yet the review also exposes troubling gaps. Freshwater systems, which harbor a disproportionate share of the world’s threatened fish species, remain critically underrepresented in the LEK literature, as do African fisheries despite the continent’s extraordinary aquatic diversity and its dependence on small-scale fishing. The authors found that formal integration of LEK into fisheries governance and biodiversity assessment remains the exception rather than the rule. Knowledge is collected, published, and then too often shelved, never translated into catch limits, protected areas, or Red List assessments. The gap between evidence and action, the review suggests, is now the field’s central challenge.

To close that gap, the researchers propose a practical three-stage framework designed to embed LEK within existing management and conservation systems rather than treating it as a parallel, informal source of insight. The framework moves from systematic collection of knowledge through validated interview and mapping protocols, to validation and integration of that knowledge alongside scientific and fisheries-dependent data, and finally to operational deployment in governance, where fishers’ evidence informs threat prioritization, spatial planning, and status assessments. The design is deliberately pragmatic: it does not require new institutions, only the willingness of existing ones to treat fishing communities as legitimate co-producers of ecological knowledge rather than as mere subjects of study or sources of raw anecdote.

The timing of this argument is not accidental. Under the Kunming-Montreal Global Biodiversity Framework, nations have committed to halting and reversing biodiversity loss, and the review’s authors argue that recognizing fishing communities as knowledge holders is both scientifically necessary and an equity imperative for meeting those commitments. The world’s data-poor fisheries will not be surveyed into submission by conventional science alone; the cost and time are simply prohibitive. But in every landing site and riverside village, there are people who have been monitoring the water all their lives. The review’s message is that conservation science has spent decades asking the wrong question about this knowledge, wondering whether it can be trusted, when the evidence now shows it can be measured, validated, and deployed. The giants of the Mekong, the sawfishes of West Africa, and the rhino rays of Goa may depend on whether that message is heard in time.

Subject of Research: Using fishers' local ecological knowledge to assess and conserve threatened aquatic biodiversity in data-poor fisheries

Article Title: Operationalizing Local Ecological Knowledge for Aquatic Biodiversity Conservation: A Systematic Review and Management Framework

Article References: Jeni, J., Swami, P., Patil, K., & Pawar, R. (2026). Operationalizing Local Ecological Knowledge for Aquatic Biodiversity Conservation: A Systematic Review and Management Framework. Environmental Management, 76(9), Article 314. https://doi.org/10.1007/s00267-026-02612-z

Image Credits: AI Generated

DOI: 10.1007/s00267-026-02612-z

Keywords: local ecological knowledge, aquatic biodiversity, small-scale fisheries, sharks and rays, freshwater fish, conservation status assessment, data-poor fisheries, fisheries governance, Kunming-Montreal Global Biodiversity Framework, shifting baselines, systematic review, participatory mapping